Clivus plate

ABSTRACT

The present disclosure generally relates to a fixation device for positioning and immobilizing at least two adjacent vertebrae. In particular, in one or more embodiments, the present disclosure relates to an anterior clivus plate that immobilizes at least two adjacent vertebrae.

FIELD OF THE INVENTION

The present disclosure generally relates to a fixation device forpositioning and immobilizing at least two adjacent vertebrae. Inparticular, in one or more embodiments, the present disclosure relatesto an anterior clivus plate that immobilizes at least two adjacentvertebrae.

BACKGROUND

Bones and bony structures are susceptible to a variety of weaknessesthat can affect their ability to provide support and structure.Weaknesses in bony structures may have many causes, includingdegenerative diseases, tumors, fractures, and dislocations. By way ofexample, rheumatoid arthritis may lead to weakness in the C1-C2articulation, resulting, for example, in basilar invagination. Advancesin medicine and engineering have provided doctors with a plurality ofdevices and techniques for alleviating or curing these weaknesses.

Typically, weaknesses in the spine are corrected by using devises thatfuse one or more vertebrae together. Common devices involve platesystems that align and maintain adjacent cervical vertebrae in a desiredposition, with desired spacing. These devices, commonly referred to asbone fixation plating systems, typically include one or more plates andscrews for aligning and holding vertebrae in a fixed position withrespect to one another. In the treatment of basilar invagination,devices that fix one or more adjacent vertebrae may be used either aloneor in combination with decompression. By way of example,occipitocervical fusion may be used for a rheumatoid arthritis patientwith basilar invagination.

Thus, there is a need for a plate system that provides structuralstability to adjacent vertebrae, for example, a plate system thatprovides structural stability to the C1-C2 articulation.

SUMMARY

An embodiment of the present invention provides an implantable device.The implantable device may comprise a bone plate having a lower surfaceconfigured to contact bone. The bone plate may comprise a base portionthat comprises a body and an extended portion. The bone plate furthermay comprise an opening in the base portion that extends from an uppersurface of the bone plate to the lower surface of the base plate. Thebone plate further may comprise an angled portion located on an oppositeend of the base portion from the extended portion. The angled portionmay be at an angle with respect to the base portion.

The features and advantages of the present invention will be readilyapparent to those skilled in the art. While numerous changes may be madeby those skilled in the art, such changes are within the spirit of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of one embodiment of a bone plate of the presentinvention.

FIG. 2 is a lateral view of the embodiment of the bone plate of FIG. 1.

FIG. 3 is a front view of another embodiment of a bone plate of thepresent invention.

FIG. 4 is a lateral view of the embodiment of the bone plate of FIG. 3.

FIG. 5 is an isometric view of one embodiment of a bone plate of thepresent invention installed in a patient.

FIG. 6 is a lateral view of one embodiment of a bone plate of thepresent invention installed in a patient.

FIG. 7 is a perspective view one embodiment of a spacer of the presentinvention installed in a patient.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present disclosure generally relates to a fixation device forpositioning and immobilizing at least two adjacent vertebra. Inparticular, in one or more embodiments, the present disclosure relatesto an anterior clivus plate that immobilizes at least two adjacentvertebrae.

FIGS. 1-2 illustrate a bone plate 10 in accordance with embodiments ofthe present invention. The bone plate 10 may be used, for example, in ananterior approach to realign and immobilize the clivus-C1-C2 for arheumatoid arthritis patient with basilar invagination. Realignment andimmobilization of the clivus-C1-C2 may be desirable, for example, for arheumatoid arthritis patient with basilar invagination of the C2ondontoid into the foramen magnum of the occiput. As will be appreciatedby those of ordinary skill in the art, with the benefit of thisdisclosure, the bone plate 10 may be a standalone device or may be usedin conjunction with one or more additional devices and/or techniques. Byway of example, the bone plate 10 may be used in combination with otherdecompression techniques, such as removal of the anterior C1 arch and/orC2 odontoid.

As illustrated in FIGS. 1-2, the bone plate 10 may include an uppersurface 12 and a lower surface 14, with the lower surface 14 configuredto contact the bone. The bone plate 10 also may include a base portion16 and an angled portion 18. The bone plate 10 further may include atleast one opening 20 formed in the base portion 16 that extends from theupper surface 12 to the lower surface 14. The bone plate 10 further mayinclude a number of holes 22 configured and adapted to receivefasteners, such as, for example, screws that will affix the bone plate10 to the bone.

As illustrated in FIGS. 1-2, the base portion 16 may include body 24 andextended portion 26 having a width narrower than the width of the body24. The width of the extended portion 26 may be, for example, sufficientto accommodate at least one screw, while the width of the base portion16 may be, for example, sufficient to accommodate at least two screws.The base portion 16 may be configured, for example, to attach to twovertebrae in the cervical region of the spine. For example, the baseportion 16 may be configured to attach to the C1 and C2 vertebrae withthe body 24 disposed over the C1 vertebrae and the extended portion 26disposed over the C2 vertebrae.

The base portion 16 further may include at least one opening 20 formedin the base portion 16 that extends from the upper surface 12 to thelower surface 14 of the bone plate 10. The surface area of the opening20 relative to the surface area of the body 24 of the base portion 16may be, for example, from about 25% to about 75%. The opening 20 may ormay not be centered in the body 24. In addition, the opening 20 may besymmetrical or asymmetrical. The opening 20 may be formed in the baseportion 16 to allow access, for example, to the space between adjacentbones. By way of example, the opening 20 may be formed in the baseportion 16 to allow access to the space between the C1 and C2 vertebrae.By way of example, fusion of the C1 and C2 vertebrae may be observed byway of the opening 20. In certain embodiments, graft materials and/orsynthetic proteins may be placed through the opening 20 to acceleratebone growth between adjacent bones, such as between the clivus and theC1 vertebrae. While the opening 20 is illustrated as generally oval, awide variety of other shapes may be suitable for the particular purpose,including, for example, circular, oblong, rectangular, square, and thelike.

The angled portion 18 may be located on the opposite end of the baseportion 16 from the extended portion 26. In general, the angled portion18 may be at an angle with respect to base portion 16, for example, toallow alignment of the angled portion 18 with the clivus 28 andalignment of the base portion 16 with vertebrae in the cervical regionof the spine. As illustrated in FIGS. 1-2, the angled portion 18 may beat an angle of about 90° with respect to the base portion 18. However,other angles may also be suitable in embodiments of the presentinvention. By way of example, the angle of the angled portion 18 withrespect to the base portion 16 may be in the range of from about 90° toabout 145°. As further illustrated in FIGS. 1-2, the base portion 16 andthe angled portion 18 may be rigidly connected. For example, the baseportion 16 and the angled portion 18 may be formed as unitary body. Inother embodiments, the base portion 16 and the angled portion 18 may benot be formed as a unitary body.

Holes 22 may be formed in the bone plate 10 that extend from the uppersurface 12 to the lower surface 14. In general, the holes 22 may beconfigured and adapted to receive fasteners, such as, for example,screws that will affix the bone plate 10 to the bone. As illustrated inFIGS. 1-2, two or more of the holes 22 may be formed in the angledportion 18 of the bone plate 10. By way of example, the two or moreholes 22 formed in the angled portion 18 may be configured and adaptedfor alignment with the clivus. In addition, two or more of the holes 22may be formed in the body 24 of the base portion 16 and at least one ofthe holes 22 may be formed in the extended portion 26 of the baseportion 16. By way of example, the two or more of holes 22 formed in thebody 24 may be configured and adapted for alignment with the C1vertebra, and the hole(s) formed in the extended portion 26 may beconfigured and adapted or alignment with the C2 vertebra. In certainembodiments, the holes 22 formed in the base portion 16 may beconfigured and adapted at the C1-C2 transarticular trajectory startingfrom the lateral mass of the C2 vertebra to the C1 vertebra. While notillustrated, an additional hole may be formed in the bottom edge of theextended portion 26. By way of example, this additional hole could beconfigured and adapted in the direction of the odontoid from the bottomedge of the extended portion 26.

The screws that may be used to connect the bone plate 10 to the bone maybe provided with a spherical head that is selectively engageable withthe spherical curvature of the hole, in certain embodiments. An elongateshaft may be connected to the spherical head to allow it to penetratethe bone. Preferably, the elongate shaft may include threads that aid infixing the bone plate 10 to the bone. It is also preferable to have ahexagonal projection to aid in gripping the screw. The length of theelongate shaft may be varied as desired. The elongate shaft of thescrews for use in the holes 22 in the angled portion 18 may have alength, for example, within a range of about 4 millimeters to about 26millimeters. In one embodiment, the elongate shaft of these screws mayhave a length of about 20 millimeters. The elongate shaft of the screwsfor use in the holes 22 in the base portion 16 may have a length, forexample, within a range of about 40 millimeters to about 65 millimeters.However, it should be understood that lengths outside the examplesdisclosed herein are encompassed by embodiments of the presentinvention.

Embodiments of the bone plate 10 also may include at least one toolengagement feature on the sides and/or top of the plate. While notillustrated, the sides of the bone plate 10 may include, for example,depressions positioned for engaging with an instrument. By way ofexample, the engaging instrument may contact the bone plate 10 in thedepressions thereby enabling the surgeon or user to control the boneplate 10 so that it may be placed in the proper position in the boneyelements of the spine. The shape of the depressions should generallyallow for the ability to have the screws positioned through a fixed orvariable angle connection.

The size of the bone plate 10 may be of any appropriate size required toperform its function. By way of example, the bone plate 10 may be ofsufficient length to extend across the clivus, C1 vertebra, and C2vertebra. In certain embodiments, the length of the bone plate 10 may bewithin a range of about 26 millimeters to about 69 millimeters. Theextended portion 26 may extend, for example, for a length of about 10millimeters to about 26 millimeters beyond an end of the body 24 that isopposite the angled portion 19. The width of the bone plate 10 may be,for example, within a range of about 30 millimeters to about 60millimeters. The width of the angled portion 18 of the bone plate 10 maybe, for example, within a range of about 10 millimeters to about 30millimeters. The width of the body 24 of the base portion 16 of the boneplate 10 may be, for example, within a range of about 30 millimeters toabout 60 millimeters. The width of the extended portion 26 of the baseportion 16 may be, for example, within a range of about 10 millimetersto about 20 millimeters. However, it should be understood that lengthsand widths outside the example ranges disclosed herein are encompassedby embodiments of the present invention.

The bone plate 10 may comprise, for example, any of a variety ofbiocompatible materials, including metals, ceramic materials, andpolymers. Examples of biocompatible materials include titanium,aluminum, cobalt-chromium, alloys, and polyethylene. Moreover, the lowersurface 14 of the bone plate 10 may include, for example, a plurality ofteeth or a porous or macrotexture surface to assist in attaching thebone plate 10 to the bone.

Referring now to FIGS. 3-4, another embodiment of the base plate 10 isillustrated in accordance with embodiments of the present invention. Asillustrated in FIGS. 3-4, the angled portion 18 may be pivotablyconnected to the base portion 16 in certain embodiments of the presentinvention. In the illustrated embodiment, the base plate 10 further mayinclude a hinge 30 connecting the base portion 16 and the angled portion18. It should be understood that the pivoted connection (e.g., hinge 30)between the angled portion 18 and the base portion 16 generally shouldallow for a variety of different angles of the angled portion 18 withrespect to the base portion. By way of example, the angle of the angledportion 18 with respect to the base portion 16 may be in the range offrom about 90° to about 145°. Moreover, the pivoted connection betweenthe angled portion 18 and the base portion 16, in certain embodiments,generally may be lockable at a predetermined angle when implanted in apatient. For example, it may be desired to lock the angled portion 16 atangle of 90° when the base plate 10 is installed in a patient.

FIGS. 5-6 illustrate positioning of the bone plate 10 in a patient inaccordance with one embodiment of the present invention. In theillustrated embodiment, a pair of vertebrae spacers 32 is shown betweenthe C1 vertebra 34 and the C2 vertebrae 36. The vertebrae spacers 32will be described in more detail below with respect to the embodiment ofFIG. 7.

As illustrated in FIGS. 5-6, the bone plate 10 may be attached to theclivus 28, the C1 vertebra 34, and the C2 vertebra 36. The plate may beintroduced superiorly at a latero-medial side of a mandible. Partialmandible removal may be required prior to positioning of the plate. Inaddition, a soft retractor blade may be used for retraction of thetrachea and larynx. In the illustrated embodiment, the bone plate 10 maybe positioned over the clivus 28, the C1 vertebra 34, and the C2vertebra 36 with the opening 20 being positioned so that the disc spacebetween the clivus 28 and the C1 vertebra 34 is accessible through theopening 20. In the pivotably connected embodiments, the angled portion18 may be locked at the desired angled, for example. Clivus screws 38may be screwed into the clivus through the holes 22 in the angledportion 18 of the bone plate 10. C1 screws 40 may be screwed into the C1vertebra 34 through the holes in body 24 of the base portion 16 of thebone plate 10. C2 screws 42 may be screwed in the C2 vertebra 36 throughthe holes in the extended portion 26 of the base portion 16 of the boneplate 10. The bone plate 10 may be attached to the clivus 28, C1vertebra 34, and C2 vertebra 36 in any suitable order. By way ofexample, in certain embodiments, the angled portion 18 of the bone platemay be attached to the clivus 28 prior to attachment of the base portion16 to the C1 vertebra 34 and the C2 vertebra 36. In other embodiments,the base portion 16 of the bone plate 10 may be attached to the C1vertebra 34 and the C2 vertebra 36 prior to attachment of the angledportion 18 to the clivus 28.

FIG. 7 illustrates a vertebrae spacer 32 in accordance with embodimentsof the present invention. The vertebrae spacer 32 may be used, forexample, in a posterior approach to restore space between the C1vertebra 34 and the C2 vertebra 36. Use of the vertebrae spacer 32, forexample, to realign and fuse the C1-C2 vertebrae may be desirable for arheumatoid arthritis patient with basilar invagination of the C2ondontoid into the foramen magnum of the occiput.

As illustrated in FIG. 7, a pair of vertebrae spacers 32 may be disposedbetween the C1 and C2 vertebrae. In the illustrated embodiment, thevertebrae spacers 32 are shaped to fit between the superior and inferiorlateral masses of the cervical spine. In another embodiment, thevertebrae spacers 32 may be u-shaped, thereby allowing for a lateralapproach to restoring space between the C1 vertebra 34 and the C2vertebra 36. In addition, each of the vertebrae spacers 32 may includeone or more holes that are configured and adapted to receive fasteners,such as, for example, screws 44 that will affix the spacers 32 to thebone. The screws 32 may be a fully or partially threaded long screw. Inother embodiments, the vertebrae spacers 32 may not include a hole forthe fastener, but instead, the vertebrae spacers 32 may be made from amaterial into which a fastener can be drilled without any pre-definedtrajectory. By way of example, vertebrae spacers 32 may be made from apolymeric material similar to MicroFuse™ granules, which are availablefrom Globus Medical, Inc.

While the vertebrae spacers 32 are illustrated in FIG. 7 as a standalonedevice, the vertebrae spacers 32 may also be used in combination withone or more additional devices and/or techniques. By way of example, thevertebrae spacers 32 may be used in combination with an anterior platethat bridges the C1 and C2 vertebrae, such the bone plate 10. By way offurther example, the vertebrae spacers 32 may be used in combinationwith wiring of the C1 and C2 vertebrae with a bone graft. By way offurther example, the vertebrae spacers 32 may be used in combinationwith a post rod and wiring of the C1 and C2 vertebrae. By way of furtherexample, the vertebrae spacers 32 may be used in combination with acable through the occiput. In yet another embodiment, a screw may beused to secure the C1 vertebra and the occiput.

The vertebrae spacers 32 may comprise, for example, any of a variety ofbiocompatible materials, including metals, ceramic materials, andpolymers. Examples of biocompatible materials include titanium,stainless steel, aluminum, cobalt-chromium, alloys, and polyethylene.Moreover, surfaces of the vertebrae spacers 32 may include, for example,a plurality of teeth or a porous or macrotexture surface to assist inattaching the vertebrae spacer to the bone.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art.

What is claimed is:
 1. An implantable system comprising: a bone platehaving a lower surface configured to contact bone, wherein the boneplate comprises: a base portion comprising a plate including a body andan extended portion, wherein the extended portion has a width less thanthe body, the body and the extended portion each including at least onehole for receiving a screw, wherein a number of holes in the body isgreater than a number of holes in the extended portion, wherein theplate extends a length such that the body is attachable to a firstvertebra and the extended portion is attachable to a second vertebra; anopening in the base portion that extends from an upper surface of thebone plate to the lower surface of the bone plate; and an angled portionlocated on an opposite end of the base portion from the extendedportion, wherein the angled portion is at an angle with respect to thebase portion, a spacer configured for positioning between a patient's C1and C2 vertebrae; and a fastener for affixing the spacer to bone,wherein the base portion and the angled portion are formed as a unitarybody, wherein base portion and the angled portion are configured to bepositioned to extend across a clivus, the first vertebra and the secondvertebra wherein the spacer includes a through hole for receiving thefastener to affix the spacer to the bone.
 2. The implantable system ofclaim 1, wherein the bone plate has a length of about 26 millimeters toabout 69 millimeters.
 3. The implantable system of claim 1, wherein thebase portion is configured for attachment to a patient's C1 and C2vertebrae with the body disposed over the C1 vertebra and the extendedportion disposed over the C2 vertebra, and wherein the angled portion isconfigured for attachment to the patient's clivus.
 4. The implantablesystem of claim 3, wherein the opening is configured to allow access tospace between the C1 vertebra and C2 vertebra.
 5. The implantable systemof claim 1, wherein the opening has an area that is about 25% to about75% of the body's surface area.
 6. The implantable system of claim 1,wherein the angled portion is at an angle of from about 90° to about145° with respect to the base portion.
 7. The implantable system ofclaim 1, wherein the extended portion extends for a length of about 10millimeters to about 26 millimeters beyond an end of the body that isopposite the angled portion, and wherein the extended portion has awidth of about 10 millimeters to about 20 millimeters.
 8. Theimplantable system of claim 1, wherein the bone plate further compriseholes for receiving fasteners for affixing the bone plate to bone.
 9. Abone fixation system comprising: a bone plate having a lower surfaceconfigured to contact bone, wherein the bone plate comprises: a baseportion comprising a plate including a body and an extended portion,wherein the extended portion has a width less than the body, the bodyand the extended portion each including at least one hole for receivinga screw, wherein a number of holes in the body is greater than a numberof holes in the extended portion, wherein the plate extends a lengthsuch that the body is attachable to a first vertebra and the extendedportion is attachable to a second vertebra; an opening in the baseportion that extends from an upper surface of the bone plate to thelower surface of the bone plate; an angled portion located on anopposite end of the base portion from the extended portion, wherein theangled portion is at an angle with respect to the base portion; and aspacer configured for positioning between a patient's C1 and C2vertebrae, a fastener for affixing the spacer to bone; and wherein thebase portion is configured for attachment to a patient's C1 and C2vertebrae with the body disposed over the C1 vertebra and the extendedportion disposed over the C2 vertebra, wherein the angled portion isconfigured for attachment to the patient's clivus, and wherein theopening is configured to allow access to space between the patient'sclivus and C1 vertebra, wherein the extended portion extends for alength of about 10 millimeters to about 26 millimeters beyond an end ofthe body that is opposite the angled portion, and wherein the extendedportion has a width of about 10 millimeters to about 20 millimeters,wherein the angled portion and the base portion are formed as a unitarybody, wherein the spacer comprises a hole for receiving the fastener foraffixing the spacer to bone.